Analysis of dengue infection transmission dynamics in Nepal using fractional order mathematical modeling

Dengue is a significant factor to the global public health issue, including Nepal. In Nepal from $2004-2022$, the largest outbreak occurred in the year 2022. Dengue infection cases appeared all over 77 districts of Nepal. The Caputo fractional order SEIR-SEI epidemic model is able to describe dengue disease transmission dynamics of present situation. For fundamental mathematical guarantees of epidemic model equations, we studied the Lipschitz and Banach contraction theorems to show that the model equations have a unique solution. The Ulam-Hyres stability is established in the model. Next generation matrix approach is used to calculate the associated basic reproduction number $R_0$. The model equilibrium points are identified, and the local asymptotic stability for disease-free equilibrium point is analyzed. Normalized forward and partial rank correlation coefficient are used for sensitivity study to identify the factors that affect dengue infection with respect to basic reproduction number. Using real data of Nepal, the model is fitted and the least square method is used for estimating parameters. Numerical scheme has been illustrated using a two-step Lagrange interpolation approach and the solution is approximated. With numerical results and sensitivity analysis, it is concluded that biting rate and death rate of mosquito are extremely sensitive to the disease transmission. The transmission increases with increasing biting rate and decreases with decreasing mosquito death rate. For the year 2022, $R_0=1.7739>1$ showing that the disease is endemic. Thus, effective control measure should be implemented to combat the dengue virus. However, further research needs to be undertaken to assess the impact of such control measures.